Conventionally, for a wiring structure of transportation equipment such as an automobile or aircraft, or of industrial equipment such as a robot, a form referred to as a wire harness in which a plurality of electric wires with terminals are bound has been used. A material constituting a conductor for an electric wire of such a wire harness is mostly copper having excellent electrically conductive characteristics or a copper-based material, such as copper alloy.
With the recent rapid enhancement in performance and capabilities of automobiles, and accordingly, with an increased number of various on-board electrical devices, control devices and the like, the number of electric wires used for these devices also tends to increase. Meanwhile, in recent years, weight reduction is strongly desired in order to enhance the fuel efficiency of an automobile, aircraft, or the like, for the purpose of environmental protection.
Thus, in order to achieve weight reduction in an electric wire, studies are being conducted on an aluminum electric wire that includes, as a conductor, aluminum whose specific gravity is approximately one-third that of copper. Pure aluminum, however, is inferior in bending characteristics to copper-based materials. For example, when the above-described aluminum electric wire is applied to a part that opens or closes, such as a door, it is broken at an early stage, and therefore, is difficult to apply to such a part. Japanese Patent Laying-Open No. 2004-134212 (PTL1), on the other hand, discloses an electric wire for an automobile wire harness that includes a conductor made of aluminum alloy having strength higher than that of pure aluminum.